This invention relates to electric machinery and, in particular, to a compact drive system suitable for use in an electric machine.
More specifically, this invention relates to a rotor assembly for use in an electric machine such as a motor or the like. Typically the rotor section of an electric motor consists of a frame mounted armature, a rotatably mounted central shaft and means to rigidly connect the shaft to the rotor frame. Oftentimes the radial distance between the shaft and the frame is comparatively large and, except for the connection therebetween, contains a good deal of unused space. In the case of fractional horsepower motors, where the available space for both the motor and its associated drive system is limited, the space between the shaft and the rotor frame represents a relatively large part of the total available space.
As disclosed in U.S. Pat. No. 613,894, the drive or transmission section of an electric motor is generally situated some distance to one side of the motor windings and is enclosed either within the motor housing itself or within a separate transmission housing. Because the size of the motor is usually fixed, efforts to reduce the size of the system usually are centered about compacting the size of the transmission. However, a point is soon reached where no further advantage can be gained in this regard. As will be disclosed below, the present invention is dedicated toward bringing the transmission or drive system of a motor within the confines of the rotor section of the motor to provide a truly compact motor and drive assembly.